Variable synchronous window

ABSTRACT

A control system/method for controlling the shifting of automated mechanical transmission systems (10) is provided. The control system/method (FIG. 4 ) defines the synchronous window ((OS*GR T )+X≧IS E  &gt;(OS*GR T )-Y) for jaw clutch engagement (for shifts other than compound upshifts) where X and Y are each greater than zero and the total synchronous window (X+Y) equals the greater of a function (fGR T ) of the numerical value of the target ratio (GR T ) or a minimum value ((X+Y) min).

RELATED APPLICATIONS

This application is related to U.S. Ser. No. 08/116,626, titledAUTOMATED MECHANICAL TRANSMISSION CONTROL SYSTEM/METHOD filed the sameday, Sep. 7, 1993, and assigned to the same assignee, Eaton Corporation,as this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a control system/method for controllingthe engagement of positive jaw clutches in an at least partiallyautomated vehicular mechanical transmission system. More particularly,the present invention relates to a control system/method for anautomated vehicular mechanical transmission system which will cause orbias the transmission jaw clutches to engage at a time when input shaftspeed is expected to be within a range of true synchronous speed, calledthe synchronous window, the extent of which is a function of thenumerical value of the target gear ratio until a minimum value isreached.

2. Description of the Prior Art

Fully or partially automated mechanical transmission systems forvehicles, such as heavy duty tractor--semitrailer vehicles, are wellknown in the prior art as may be seen by reference to U.S. Pat. Nos.4,361,060; 4,595,986; 4,614,126; 4,648,290; 4,676,115; 4,784,019;4,874,881; 4,899,607; 5,050,427 and 5,136,897, the disclosures of all ofwhich are incorporated herein by reference. Briefly, these automatedtransmission systems typically utilized sensors to provide informationsuch as drive mode or shift selection, throttle pedal position,currently engaged ratio and engine, input shaft and/or output shaftspeeds to a controller. The controller, typically microprocessor based,would process these inputs according to predetermined logic rules toissue command output signals to various actuators such as an enginefueling device, a master clutch operator and/or a transmission shiftactuator. Engine fueling manipulation, an input shaft or engine brakeand/or a power synchronizer were typically used to cause the input shaftand its associated gearing to rotate at a substantially synchronousrotational speed relative to the output shaft rotational speed andtarget gear ratio.

In view of the known response times for the various actuators, as theinput shaft speed ("IS") approached the synchronous window, i.e. theproduct of output shaft speed times the numerical value of the targetgear ratio (OS *GR_(TARGET)) plus or minus an acceptable value (usuallyabout±40 RPM), the jaw clutches associated with the target gear ratiowere commanded to engage with the expectation that the expected inputshaft speed (IS_(E)) would be within the acceptable range as the targetratio jaw clutch members came into initial engagement.

While the prior an vehicular automated mechanical transmission systemcontrols were generally satisfactory and provided well synchronized jawclutch engagement, they were not totally satisfactory as, at the lowerspeed ratios (higher numerical reduction ratios), the synchronouswindows were more restricted than necessary making achieving synchronousmore difficult or time-consuming than necessary.

SUMMARY OF THE INVENTION

In accordance with the present invention, the drawbacks of the prior artare overcome or minimized by the provision of a vehicular fully orpartially automated mechanical transmission system control method/systemwhich, for both upshifts and downshifts, will tend to cause jaw clutchengagement when (OS*GR_(T))+X≧IS_(E) ≧(OS*GR_(T))-Y where:

IS_(E) =expected input shaft speed,

OS=output shaft speed,

GR_(T) =the numerical value of the gear reduction in the target ratio,

X≧0

Y≧0, and

X+Y=a function of GR_(T) or a minimum value (X+Y)_(MIN), whichever isgreater.

The value to the function is related of the most harsh acceptable shiftin a particular ratio, see for example, U.S. Pat. No. 5,052,535, thedisclosure of which is incorporated herein by reference.

In the lower gear ratios (higher numerical gear reductions), the valueof X+Y will vary with the value of the numerical gear reduction of thetarget gear ratio until a minimum value, (X+Y)_(MIN), is reached, suchas 30 RPM.

A possible exception to the above embodiments will occur with range typecompound transmissions, see U.S. Pat. No. 5,193,410, the disclosure ofwhich is incorporated herein by reference, where, in a compound rangeupshift, to assure proper operation of the range section synchronizers,shift quality may be compromised by biasing the transmission to engagethe main section jaw clutch of the target gear ratio such that(OS*GR)>IS≧(OS*GR) -K where K is a positive RPM.

In the following descriptions of the preferred embodiments, thispossible exception will be understood.

Accordingly, it is an object of the present invention to provide acontrol system/method for a vehicular at least partially automatedmechanical transmission system which will sequence jaw clutch engagementto occur, or tend to occur, for the lower speed ratios, more quickly andeasily than in the prior art.

This and other objects and advantages of the present invention willbecome apparent from a reading of the description of the preferredembodiment taken with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an automated mechanicaltransmission system of the type particularly well suited to becontrolled by the control methods/system of the present invention.

FIG. 1A is a schematic illustration of a digital microprocessor-basedCPU.

FIG. 2 is a schematic illustration of the vehicular mechanicaltransmission system controlled by the control system/method of thepresent invention.

FIG. 3 is a partial cross-sectional view of a typical positive jawclutch assembly utilized in the automated mechanical transmissionsystems of FIGS. 1 and 2.

FIG. 4 is a schematic illustration, in flow chart format, of the controlsystem/method of the present invention.

FIG. 5 is a chart illustrating the numerical gear reduction ratios, andtypical tolerance factor values, for a transmission of the typeillustrated in FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Certain terminology will be used in the following description forconvenience and reference only and will not be limiting. The words"upwardly", "downwardly", "rightwardly", and "leftwardly" will designatedirection in the drawings to which reference is made. The words"inwardly" and "outwardly" will refer to directions toward and awayfrom, respectively, the geometric center of the device and designatedparts thereof. Said terminology will include the words abovespecifically mentioned, derivatives thereof and words of similar import.

The term "compound transmission" is used to designate a change speed orchange gear transmission having a multiple forward speed maintransmission section and a multiple speed auxiliary transmission sectionconnected in series whereby the selected gear reduction in the maintransmission section may be compounded by further selected gearreduction in the auxiliary transmission section. "Synchronized clutchassembly" and words of similar import shall designate a clutch assemblyutilized to nonrotatably couple a selected gear to a shaft by means of apositive clutch in which attempted engagement of said clutch isprevented until the members of the clutch are at substantiallysynchronous rotation. In "synchronized clutch assemblies" relativelylarge capacity friction means are utilized with the clutch members andare sufficient, upon initiation of a clutch engagement, to cause theclutch members and all members rotating therewith to rotate atsubstantially synchronous speed.

The term "upshift" as used herein, shall mean the shifting from a lowerspeed gear ratio into a higher speed gear ratio. The term "downshift" asused herein, shall mean the shifting from a higher speed gear ratio to alower speed gear ratio.

A vehicular automated mechanical transmission system 10 of the typeparticularly well suited for control by the control system/method of thepresent invention is schematically illustrated in FIGS. 1 and 2. Fullyand partially automated mechanical transmission systems are well knownin the prior art as may be seen by reference to the above-mentioned U.S.Pat. Nos. 4,361,060; 4,595,986; 4,614,126; 4,648,290; 4,676,115;4,784,019; 5,053,961 and 5,136,897.

FIG. 1 schematically illustrates a vehicular automated mechanicaltransmission system 10 including an automated multiple speed change geartransmission 11 driven by a fuel controlled engine E, such as awell-known diesel engine, through a coupling such as a friction masterclutch C. The output of the automated transmission 11 is output shaft 90which is adapted for driving connection to an appropriate vehiclecomponent such as the differential of a drive axle, a transfer case, orthe like, and is well known in the prior art.

The crankshaft 20 of engine E will drive the driving plates 18 of masterfriction clutch C which are frictionally engageable to driven plates 22for driving the input shaft 16 of transmission 11.

The above-mentioned power train components are acted upon and/ormonitored by several devices, each of which will be discussed brieflybelow. These devices include a throttle pedal position or throttleopening monitor assembly 21 which senses the operator set position ofthe operator control throttle device THL, a fuel control device 23controlling the amount of fuel to be supplied to engine E, engine speedsensor 25 which senses the rotational speed of the engine, a clutchoperator 27 which engages and disengages master clutch C and which mayalso provide information as to the status of the clutch, an input shaftspeed sensor 98 for sensing the rotational speed of transmission inputshaft 16, a transmission operator 29 which is effective to shift thetransmission 11 into a selected gear ratio and to provide a signalindicative of the gear neutral condition and/or the currently engagedgear ratio, and an output shaft speed sensor 100 for sensing therotational speed of the output shaft 90.

The transmission shift operator 27 may be of any well-known type,examples of which may be seen by reference to above-mentioned U.S. Pat.Nos. 4,874,881 and 4,899,607. FIG. 1A is a schematic illustration ofmicroprocessor-based CPU 31.

The above-mentioned devices supply information to and/or accept commandsignals from the central processing unit controller 31. The centralprocessing unit 31 may include analog and/or digital electroniccalculation and logic circuitry as is well known in the prior art.Preferably, the central processing unit will be microprocessor based, anexample of which may be seen by reference to above-mentioned U.S. Pat.No. 4,595,986. The central processing unit 31 will also receiveinformation from a shift control assembly 33 by which the vehicleoperator may select a reverse (R) neutral (N) or forward drive (D) modeof operation of the vehicle. An electrical power source (not shown)and/or a source of pressurized fluid (not shown) provide electricaland/or pneumatic power to the various sensing, operating and/orprocessing units.

Drive train components and controls therefore of the type describedabove are known in the prior art and may be appreciated in greaterdetail by reference to U.S. Pat. Nos. 4,595,986; 4,576,065 and4,445,393, the disclosures of all of which are hereby incorporated byreference. The sensors 21, 23, 25, 27, 98, 29 and 100 may be of anyknown type of construction for generating analog or digital signalsproportional to the parameter monitored thereby. Similarly, operators23, 27 and 29 may be of any known electric, pneumatic orelectro-pneumatic type for executing operations in response to commandoutput signals from the central processing unit 31.

In addition to direct inputs, the central processing unit 31 may beprovided with circuitry for differentiating the input signals from atleast sensors 23, 25 and/or 98 to provide a calculated signal indicativeof the rotational acceleration and/or deceleration of engine,transmission input shaft and/or transmission output shaft. CPU 31 mayalso be provided with circuitry and logic rules to compare the inputsignals from sensor 98 and 100 to verify and identify that thetransmission 11 is engaged in a particular gear ratio, etc.

The structural details of automated transmission 11 may be seen byreference to FIG. 2. Compound transmission 11 comprises a multiple speedmain transmission section 12 connected in series with a range typeauxiliary section 14. Transmission 11 is housed within a housing H andincludes an input shaft 16 driven by a prime mover such as diesel engineE through a selectively disengaged, normally engaged friction masterclutch C having an input or driving portion 18 drivingly connected tothe engine crankshaft 20 and a driven portion 22 rotatably fixed to thetransmission input shaft 16.

An input shaft brake B, operated by CPU 31, is preferably provided toprovide quicker upshifting as is well known in the prior art.

Transmissions similar to mechanical transmission 11 are well known inthe prior an and may be appreciated by reference to U.S. Pat. Nos.3,105,395; 3,283,613; 4,754,665 and 5,193,410, the disclosures of whichare incorporated by reference.

In main transmission section 12, the input shaft 16 carries an inputgear 24 for simultaneously driving a plurality of substantiallyidentical countershaft assemblies 26 and 26A at substantially identicalrotational speeds. The two substantially identical countershaftassemblies are provided on diametrically opposite sides of mainshaft 28which is generally coaxially aligned with the input shaft 16. Each ofthe countershaft assemblies comprises a countershaft 30 supported bybearings 32 and 34 in housing H, only a portion of which isschematically illustrated. Each of the countershafts is provided with anidentical grouping of countershaft gears 38, 40, 42, 44, 46 and 48,fixed for rotation therewith. A plurality of mainshaft gears 50, 52, 54,56 and 58 surround the mainshaft 28 and are selectively clutchable, oneat a time, to the mainshaft 28 for rotation therewith by sliding jawclutch collars 60, 62 and 64 as is well known in the prior art. Clutchcollar 60 may also be utilized to clutch input gear 24 to mainshaft 28to provide a direct drive relationship between input shaft 16 andmainshaft 28.

Typically, clutch collars 60, 62 and 64 are axially positioned by meansof shift forks associated with the actuator 27 as well known in theprior art. Clutch collars 60, 62 and 64 may be of the well known doubleacting nonsynchronized double acting jaw clutch type.

Mainshaft gear 58 is the reverse gear and is in continuous meshingengagement with countershaft gears 48 by means of conventionalintermediate idler gears (not shown). It should also be noted that whilemain transmission section 12 does provide five selectable forward speedratios, the lowest forward speed ratio, namely that provided bydrivingly connecting mainshaft drive gear 56 to mainshaft 28, if oftenof such a high gear reduction it has to be considered a low or "creeper"gear which is utilized only for starting of a vehicle under severeconditions and, is not usually utilized in the high transmission range.Accordingly, while main transmission section 12 does provide fiveforward speeds, it is usually referred to as a "four plus one" mainsection as only four of the forward speeds are compounded by theauxiliary range transmission section 14 utilized therewith.

Jaw clutches 60, 62 and 64 are three-position clutches in that they maybe positioned in the centered, nonengaged position as illustrated, or ina fully rightwardly engaged or fully leftwardly engaged position bymeans of actuator 27. As is well known, only one of the clutches 60, 62and 64 is engageable at a given time and main section interlock means(not shown) are provided to lock the other clutches in the neutralcondition.

Auxiliary transmission range section 14 includes two substantiallyidentical auxiliary countershaft assemblies 74 and 74A, each comprisingan auxiliary countershaft 76 supported by bearings 78 and 80 in housingH and carrying two auxiliary section countershaft gears 82 and 84 forrotation therewith. Auxiliary countershaft gears 82 are constantlymeshed with and support range/output gear 86 while auxiliary sectioncountershaft gears 84 are constantly meshed with output gear 88 which isfixed to transmission output shaft 90.

A two-position synchronized jaw clutch assembly 92, which is axiallypositioned by means of a shift fork (not shown) and the range sectionshifting actuator assembly (not shown), is provided for clutching eithergear 86 to mainshaft 28 for low range operation or gear 88 to mainshaft28 for direct or high range operation of the compound transmission 10.

Although the range type auxiliary section 14 is illustrated as atwo-speed section utilizing spur or helical type gearing, it isunderstood that the present invention is also applicable to compoundtransmissions utilizing splitter or combined splitter/range typeauxiliary sections, having three or more selectable range ratios and/orutilizing planetary type gearing. Also, any one or more of clutches 60,62 or 64 may be of the synchronized jaw clutch type and transmissionsections 12 and/or 14 may be of the single countershaft type.

FIG. 3 illustrates a typical jaw clutch structure utilized with heavyduty mechanical change gear transmissions of the type automated by thecontrol system/method of the present invention. Briefly, it may be seenthat mainshaft gears 54 and 56 surround mainshaft 28 in a radiallyfloating manner and are maintained in a predetermined axial positionrelative to mainshaft 28 by means of spacer members 102 as may be seenin greater detail by reference to U.S. Pat. Nos. 3,894,621 and4,949,589, the disclosures of which are hereby incorporated byreference. Clutch collars 62 and 64 are provided with internal spline104 which are slidably engaged with external splines 106 provided on theouter diameter surface of mainshaft 28. The clutch collars 62 and 64 areaxially positioned on the mainshaft 28 by means of shift forks 108 and110, respectively which are controlled by the shift actuator 27. Shiftcollar 62 is provided with jaw clutch teeth 112 which may be selectivelyengaged with jaw clutch teeth 114 provided on the main shaft gear 54.Shift collar 64 is provided with jaw clutch teeth 116 which may beselectively engaged with jaw clutch teeth 118 provided on the mainshaftgear 56.

As is known, to achieve a smooth engagement of gear 54 to mainshaft 28clutch collar 62 must be moved rightwardly to bring clutch teeth 112into engagement with clutch teeth 114 at a time when the mainshaft gear54 is rotating at a rotational speed which is substantially equal to therotational speed of mainshaft 28 and the clutch collar 62 which isrotating therewith. Assuming that the auxiliary range section 14 remainsengaged in either the high or low speed ratio thereof, the rotationalspeed of the clutch collars and the mainshaft 28 will be determined bythe ratio of the range section and the rotational speed of the outputshaft (OS). During the time of the gear change operation in the maintransmission section 12, the ground speed of the vehicle, and thus therotational speed of output shaft 90, will remain substantially constant.The rotational speed of the mainshaft gears 54 and 56 is a function ofthe gear ratios thereof and the rotational speed of the input shaft 16(IS). Accordingly, to achieve a substantially synchronous condition forengagement of one of the main shaft gears, the speed of the input shaft16 is modulated by means of controlled fueling of engine E and/oroperation of upshift brake B. As is well known in the prior art, atprecisely synchronous conditions for engagement of a particular targetgear ratio, IS=OS ×GR_(TARGET) and, if clutch C is fully engaged withoutslip, ES=IS=OS×GR_(TARGET). In practice, acceptable shifts can beachieved if the jaw clutch members are out of synchronous by apredetermined amount, such as about 20 to 40 RPM. Accordingly, thesynchronous shift window for engaging a particular target gear ratiowill be IS=(OS×GR_(TARGET))±about 20 to 40 RPM.

In the prior art fully or partially automated transmission systems, thereaction time of the various actuators was a known or determined value,as was the rate of change of the rotational speed of the engine and/orinput shaft. Based upon these parameters, as the input shaft approacheda substantially synchronous speed, the ECU 31 would issue command outputsignals to the various actuators to initiate a shift into the selectedtarget gear ratio with the expectation that the clutch teeth would comeinto engagement at a time when the expected input shaft rotational speed(IS_(E)) would equal the product of the target gear ratio multiplied bythe output shaft speed plus or minus the predetermined constant value.

According to the control system/method of the present invention,schematically illustrated in flow chart format in FIG. 4, thesynchronous window is defined such that the ECU will cause to tend tocause jaw clutch engagement when (OS×GR_(TARGET))+X>IS_(E)>(OS×GR_(TARGET))-Y where:

IS_(E) =expected input shaft speed, OS=output shaft speed, GR_(TARGET)=the numerical value of the gear reduction in the target gear ratio, Xis greater than zero, Y is greater than zero, and the sum of X+Y is thegreater of a function of GR_(T) or a minimum value where the varies withthe value of GR_(T).

Referring to the flow chart representation of the control system/methodof the present invention as shown in FIG. 4, the value IS_(E) is theexpected value of the input shaft rotational speed after the passage ofthe period of time generally equal to that period of time for thevarious actuators to respond to command output signals from the CPU 31to cause the jaw clutch teeth associated with the target gear ratio tocome into initial engagement.

The value of the larger of X or Y is selected as a function of the mostharsh acceptable shift in the target gear ratio, see for example,above-mentioned U.S. Pat. No. 5,052,535.

In the lower gear ratios (higher numerical gear reductions), the valuesof X+Y may vary with the value of the numerical gear reduction of thetarget gear ratio until a minimum value is reached, such as 45 RPM.Referring to FIG. 5, X+Y is taken as the greater of ((20*GR)-19) or 45.

In the lower speed, higher gear reduction, ratios, such as first (1st)through fifth (5th) speed ratios in a ten forward speed transmission, itis desirable and permissible to use a somewhat more expansivesynchronous window. To assure that an upshift can be made when a vehicleis traveling tip a grade, i.e. both ES/IS and OS will be decreasing, alarger synchronous window is required. Further, in the speed ratios, thelarger gear reduction will result in a lower or softer driveline springrate which tend to dampen the harshness of an out of synchronous jawclutch engagement.

A possible exception to the above will occur with range type compoundtransmissions, see above-mentioned U.S. Pat. No. 5,193,410, where, in acompound range upshift, such as 5th to 6th upshift or a 5th to 7th skipupshift, to assure proper operation of the range section synchronizers,shift quality may be compromised by causing the transmission to engagethe main section jaw clutch of the target gear ratio such that the inputshaft is always rotating at less than true synchronous speed, i.e.(OS*GR)>IS≧(OS*GR) - K. In the descriptions of the preferredembodiments, this possible exception will be understood.

The description of the preferred embodiments of the present invention isby way of example only and various modification and/or rearrangement ofthe parts and/or steps thereof are contemplated without departing fromthe spirit and the scope of the invention as hereinafter claimed.

I claim:
 1. A method for controlling dynamic non-compound shifting of avehicular automated mechanical transmission system (10) of the typecomprising a multiple-speed mechanical transmission having a pluralityof selectable gear ratios (GR), each having engageable and disengageablepairs of non-blocked positive jaw clutch members (112/114, 116/118)associated therewith, said transmission having an input shaft (16)drivingly connected to a prime mover (E) by a non-positive coupling (C)and an output shaft (90) for driving connection to vehicular drivewheels, each of said pairs of positive jaw clutch members including afirst jaw clutch member (114/118) drivingly associated with said inputshaft and a second jaw clutch member (112/116) drivingly associated withsaid output shaft, a control unit (CPU) for receiving input signalsincluding input signals indicative of input shaft rotational speed (IS)and output shaft rotational speed (OS) and for processing same accordingto predetermined logic rules to issue command output signals to systemactuators (23, 27, 29), including a transmission actuator (27) effectiveto selectively engage and disengage selected pairs of said positive jawclutch members, said transmission actuator having a response timecomprising the time required for said actuator to respond to a commandoutput signal and move a selected pair of positive jaw clutch membersfrom a normally disengaged position to a position of initial positiveengagement, said method comprising the steps of:determining arequirement for a non-compound shift from a transmission neutralcondition into a target gear ratio (GR_(T)); determining a maximumacceptable value of difference of rotational speed of the first andsecond jaw clutch members associated with said target gear ratio atinitial positive engagement thereof as the greater of (i) a minimumvalue and (ii) a function of the numerical value of the target gearratio increasing and decreasing, respectively, with increasing anddecreasing values, respectively, of said numerical value; sensingcurrent values of said input signals indicative of input shaft andoutput shaft rotational speed; determining, as functions of at least oneof (i) said current value of said input signal indicative of input shaftrotational speed, (ii) said current value of said input signalindicative of output shaft rotational speed, and (iii) said responsetime, values indicative of expected rotational speeds of said first andsecond jaw clutch members associated with said target gear ratio atinitial positive engagement thereof in the event of an instantaneouscommand to said actuator to initiate engagement of said first and secondjaw clutch members associated with said target gear ratio; if thedifference between said expected rotational speeds is no greater thansaid maximum acceptable value of difference, issuing command outputsignals to said actuator to initiate engagement of the pair of positivejaw clutch members associated with said target gear ratio; andresponsive to said command output signals, causing initiation ofengagement of said pair of positive jaw clutch members associated withsaid target gear ratio.
 2. The method of claim 1 further comprisingissuing command output signals to said actuators to initiate engagementof the pair of positive clutch members associated with a target gearratio (GR_(T)) only when the expression (OS*GR_(T))+X ≧IS_(E)>(OS*GR_(T))-Y is true where:OS=output shaft speed (in RPM), GR_(T)=numerical ratio of the target gear ratio, IS_(E) =the expected inputshaft speed (in RPM) at the time of initial positive engagement of thepair of positive clutch members associated with said target gear ratio,X>0, Y>0, and X+Y=the larger of fGR_(T) or (X+Y)_(MIN) where fGR_(T) isa function of GR_(T) increasing and decreasing in value, respectively,with increasing and decreasing values, respectively, of GR_(T), and(X+Y)_(MIN) is a constant minimum value.
 3. The method of claim 2wherein (X+Y)_(MIN) equals about 45 RPM.
 4. The method of claim 3wherein (X+Y)_(MIN) equals about 30 RPM.
 5. A control system forcontrolling dynamic non-compound shifting of a vehicular automatedmechanical transmission system (10) of the type comprising amultiple-speed mechanical transmission having a plurality of selectablegear ratios (GR), each having engageable and disengageable pairs ofnon-blocked positive jaw clutch members (112/114, 116/118) associatedtherewith, said transmission having an input shaft (16) drivinglyconnected to a prime mover (E) by a non-positive coupling (C) and anoutput shaft (90) for driving connection to vehicular drive wheels, eachof said pairs of positive jaw clutch members including a first jawclutch member (114/118) drivingly associated with said input shaft and asecond jaw clutch member (112/116) drivingly associated with said outputshaft, a control unit (CPU) for receiving input signals including inputsignals indicative of input shaft rotational speed (IS) and output shaftrotational speed (OS) and for processing same according to predeterminedlogic rules to issue command output signals to system actuators (23, 27,29), including a transmission actuator (27) effective to selectivelyengage and disengage selected pairs of said positive jaw clutch members,said transmission actuator having a response time comprising the timerequired for said actuator to respond to a command output signal andmove a selected pair of positive jaw clutch members from a normallydisengaged position to a position of initial positive engagement, saidcontrol system comprising:means for determining a requirement for anon-compound shift from a transmission neutral condition into a targetgear ratio (GR_(T)); means for determining a maximum acceptable value ofdifference of rotational speed of the first and second jaw clutchmembers associated with said target gear ratio at initial positiveengagement thereof as the greater of (i) a minimum value and (ii) afunction of the numerical value of the target gear ratio increasing anddecreasing, respectively, with increasing and decreasing values,respectively, of said numerical value; means for sensing current valuesof said input signals indicative of input shaft and output shaftrotational speed; means for determining, as functions of at least one of(i) said current value of said input signal indicative of input shaftrotational speed, (ii) said current value of said input signalindicative of output shaft rotational speed, and (iii) said responsetime, values indicative of expected rotational speeds of said first andsecond jaw clutch members associated with said target gear ratio atinitial positive engagement thereof in the event of an instantaneouscommand to said actuator to initiate engagement of said first and secondjaw clutch members associated with said target gear ratio; meanseffective, if the difference between said expected rotational speeds isno greater than said maximum acceptable value of difference, for issuingcommand output signals to said actuator to initiate engagement of thepair of positive jaw clutch members associated with said target gearratio; and means, responsive to said command output signals, for causinginitiation of engagement of said pair of positive jaw clutch membersassociated with said target gear ratio.
 6. The control system of claim 5wherein said means for issuing command output signals to said actuatorsto initiate engagement of the pair of positive clutch members associatedwith a target gear ratio (GR_(T)) issues said command output signalsonly when the expression (OS*GR_(T))+X≧IS_(E) >(OS*GR_(T))-Y is truewhere:OS =output shaft speed (in RPM), GR_(T) =numerical ratio of thetarget gear ratio, IS_(E) =the expected input shaft speed (in RPM) atthe time of initial positive engagement of the pair of positive clutchmembers associated with said target gear ratio, X>0, Y>0, and X+Y=thelarger of fGR_(T) or (X+Y)_(MIN) where fGR_(T) is a function of GR_(T)increasing and decreasing in value, respectively, with increasing anddecreasing values, respectively, of GR_(T), and (X+Y)_(MIN) is aconstant minimum value.
 7. The system of claim 6 wherein (X+Y)_(MIN)equals about 45 RPM.
 8. The system of claim 7 wherein (X+Y)_(MIN) equalsabout 30 RPM.
 9. A machine for controlling dynamic non-compound shiftingof a vehicular automated mechanical transmission system (1 0) of thetype comprising a multiple-speed mechanical transmission having aplurality of selectable gear ratios (GR), each having engageable anddisengageable pairs of non-blocked positive jaw clutch members (112/114,116/118) associated therewith, said transmission having an input shaft(16) drivingly connected to a prime mover (E) by a non-positive coupling(C) and an output shaft (90) for driving connection to vehicular drivewheels, each of said pairs of positive jaw clutch members including afirst jaw clutch member (114/118) drivingly associated with said inputshaft and a second jaw clutch member (112/116) drivingly associated withsaid output shaft, a control unit (CPU) for receiving input signalsincluding input signals indicative of input shaft rotational speed (IS)and output shaft rotational speed (OS) and for processing same accordingto predetermined logic rules to issue command output signals to systemactuators (23, 27, 29), including a transmission actuator (27) effectiveto selectively engage and disengage selected pairs of said positive jawclutch members, said transmission actuator having a response timecomprising the time required for said actuator to respond to a commandoutput signal and move a selected pair of positive jaw clutch membersfrom a normally disengaged position to a position of initial positiveengagement, said machine comprising:(1) input signal receiving means forreceiving said input signals; (2) data processing means including logicrules for:(a) determining a requirement for a non-compound shift from atransmission neutral condition into a target gear ratio (GR_(T)); (b)determining a maximum acceptable value of difference of rotational speedof the first and second jaw clutch members associated with said targetgear ratio at initial positive engagement thereof as the greater of (i)a minimum value and (ii) a function of the numerical value of the targetgear ratio increasing and decreasing, respectively, with increasing anddecreasing values, respectively, of said numerical value; (c) sensingcurrent values of said input signals indicative of input shaft andoutput shaft rotational speed; (d) determining, as functions of at leastone of (i) said current value of said input signal indicative of inputshaft rotational speed, (ii) said current value of said input signalindicative of output shaft rotational speed, and (iii) said responsetime, values indicative of expected rotational speeds of said first andsecond jaw clutch members associated with said target gear ratio atinitial positive engagement thereof in the event of an instantaneouscommand to said actuator to initiate engagement of said first and secondjaw clutch members associated with said target gear ratio; (e) if thedifference between said expected rotational speeds is no greater thansaid maximum acceptable value of difference, determining to causeissuing of command output signals to said actuator to initiateengagement of the pair of positive jaw clutch members associated withsaid target gear ratio; and (3) output signal issuing means for issuingsaid command output signals to said actuator.
 10. The machine of claim 9wherein said logic rules further comprise issuing command output signalsto said actuators to initiate engagement of the pair of positive clutchmembers associated with a target gear ratio (GR_(T)) only when theexpression (OS*GR_(T))+X≧IS_(E) >(OS*GR_(T))-Y is true where:OS=outputshaft speed (in RPM), GR_(T) =numerical ratio of the target gear ratio,IS_(E) =the expected input shaft speed (in RPM) at the time of initialpositive engagement of the pair of positive clutch members associatedwith said target gear ratio, X>0, Y>0, and X+Y=the larger of fGR_(T) or(X+Y)_(MIN) where fGR_(T) is a function of GR_(T) increasing anddecreasing in value, respectively, with increasing and decreasingvalues, respectively, of GR_(T), and (X+Y)_(MIN) is a constant minimumvalue.